Michael Eavis has just been for an early-morning swim, and is explaining the relationship between work, pleasure and the tax man. Take his swimming pool. Originally, it served as the water system for the Glastonbury festival, then for the rest of the year he swam in it. "So the tax man took 50-50. Half for work, half for pleasure. Hahaha!"

The dairy farmer who founded the festival 43 years ago has the most joyous laugh I've ever heard. And he laughs a lot – at the oddities of life, the people who stood in his way, those who helped, his endless good luck, the wonder of it all.

We're in his red Land Rover heading for a festival in a field in Pilton, Somerset. But this is nothing to do with music. He's a judge in the cheese competition at the Royal Bath and West show a couple of miles away from his own farm, which will host the Rolling Stones for the first time next week, plus 2,000 other acts on 58 stages. Glastonbury is the largest greenfield and performing arts festival in the world. This year Eavis has had to turn away 500,000 people willing to pay £205 a pop. It all started in a field in 1970 when Marc Bolan turned up in his felt-lined Thunderbird sports car and did an acoustic set (folky Al Stewart and prog-rockers Quintessence were also on the bill – tickets were £1.)

Everybody knows Michael Eavis around here. White, moustachio-less beard, supremely bald, huge smile, always in shorts no matter the weather, he looks as if he's stepped straight out of a Thomas Hardy novel. Some locals bitch about him – jumped-up farmer, acts as if he owns Pilton, who is he to say what transport can and can't come into the village, makes a fortune at our expense, it's not only the cows he milks. Others adore him – he gives £2m a year to charity, helps the local schools, man of principle, this place would be nothing without him, best cows in the area.

It's 9.25am and he's due at the cheese pavilion in five minutes, but parking is not proving easy.

"From here all the way down is disabled, Mr Eavis," says the attendant. "The nearest car park to the cheese is the blue one. Have you been in the blue car park?"

"Where's blue then? I'm a judge at half nine you see."

"Go back up the road, turn left and the blue gate is right in front of you."

"Thank you very much, thank you."

Ten minutes later at the blue car park an officious security man takes great pleasure in stalling Eavis.

"Hello, hello, hello. You've got to stop, Michael Eavis. The problem is you haven't got the right pass."

"I've got all sorts of passes. I've got to go, I'm a judge. They sent me here."

"That's not the point. You need the right car pass to get into this section."

"Ah let me go, go on!"

"You should know the rules. I can't let anyone in."

"I shouldn't be here at all really. I've got too much on, and I'm doing them a bloody favour to judge the cheese." Eavis is peeved. "Who d'you work for?"

It turns out the security man works for a company that Eavis fell out with.

"We sacked that lot," he says to me. "Payback time! Hahaha!" And his humour returns.

Michael Eavis's life outside Glastonbury festival – judging cheese at the Royal Bath and West show 2013 in Shepton Mallet. Photograph: Sam Frost Sam Frost/Sam Frost

Ten years ago, I met Eavis, now 77, at Worthy Farm with his daughter, Emily, who runs the festival with him. He seemed older then, a man in decline. His wife, Jean, with whom he started the festival, had died recently, and he was lost. He's remarried since then, and says the third Mrs Eavis, a retired midwife, has given him a new lease of life.

When we first met he also said it was his ambition to host the Stones at Glastonbury, but it would never happen because they wanted too much money. So what changed? "The Stones wanted to do it; that's the secret really. Who wouldn't want to do it? The point is they're exceedingly generous to us. There's no greed, no grabbing. They've got their 50-year anniversary." Eavis is fully aware of the cachet attached to his festival. "Everybody's done it except them, you see. They knew they were conspicuous by their absence. This is England's pride and joy. Americans love it. We've been chosen as the best festival in the world so many years running."

He's trying out the purple car park as he talks. "Can I get closer?" he asks another attendant. "Can you help me in? … The U2 did it two years ago as well. They didn't do it for money either. It cost them $2m to actually play here, the U2." It's common, he says, for major artists with huge shows to lose money playing Glastonbury. "Paul McCartney lost a lot of money here."

Eavis chortles his way through the cheese judging, pronounces that he's partial to a bit of cheddar, which his grandfather used to produce on the farm (the family have been there 150 years), and finally tells me he's cheesed off. One of his old enemies, a councillor who did his damnedest to destroy the festival, is in his eyeline. "I very nearly punched him once. His sole mission in life was to stop the festival. He didn't succeed," he says with a glint in his eye.

As a puritan Methodist, Eavis is an unlikely creator of Glastonbury. He doesn't approve of drugs, doesn't think much of alcohol. For two months before the festival he doesn't touch a drop to keep a clear head, and he can often be heard railing against the evils of booze. "Terrible drug, alcohol. The Muslims got it right on that, actually. If you've got responsibility, you shouldn't drink." Yet he says in some ways his religion has shaped the festival in a positive way – the risk-taking and embracing of freedom comes from his Methodism.

In the early days, he let in people who were skint or unemployed for nothing. Again, the Methodism. In the mid-80s he allowed a convoy of travellers who had been banned from Stonehenge into Glastonbury. They repaid him by burning 50 Land Rovers. That was when the festival reached its nadir, he says and he and his second wife, Jean, considered stopping the festival for good.

So you embrace the great unwashed, I say glibly, and they repay you by rioting. "Well I didn't care about them smelling." He pauses, and starts again. "Actually, I forced them to shower when they came on site" Amazing – the travellers were too smelly for Glastonbury. He laughs. "The real problem was the violence. They came on site with knives."

But he felt it was wrong to turn them away. "The fact that they couldn't go to Stonehenge, and they were stopped by the army. It went against the grain for me to do so much to get rid of a few hippies. I was in a position to let them in, and some of them were very creative, and they were on the same wavelength about CND and the whole green thing." Eavis is a natural optimist. It was a bad year, but out of it came some good – a working relationship with installation artist Joe Rush, one of the most obstreperous of the travellers, who has contributed regularly to Glastonbury ever since.

Eavis and Rush are collaborating on a stunt today at the Bath and West, and he becomes fidgety when Rush doesn't turn up on time. He fears that Rush may be in the wrong mood; that he's put off by the conservatism of the agricultural show.

In general, he worries more than he did when he was a young man. With age comes a sense of responsibility, he says. Plus, today's punters are paying so much. "Poor people have paid £200 for a ticket, another £200 to get here and food, so £400-500, and not to deliver to those people … that's what worries me more than anything. At 30 I didn't care that much, I just wanted to put a show on. When you get older, when you've got 17 grandchildren, you get more mature, and you get more concerned about people's wellbeing, don't you?"

Two experiences were crucial in shaping Michael Eavis. At nine he left the village to board at the upmarket Wells Cathedral school. His mother, a headteacher, wanted the best for him. Was he mixing with posher boys? "Kind of, yeah. They were really bright." After school he went to sea, and dreamed of becoming an admiral. But when he was 19 his father died and he was called home to work on the farm. He also spent two years working in coalmines; from being a bit of an oik when he started school, he was now the posh lad down the mines.

Forty-three years ago, Eavis started the festival with a £5,000 overdraft. Now that figure's up to £1.3m. Could he pay it off? "I'd feel guilty if I did. Isn't it funny?" Why? "We give away £2m a year to Greenpeace, Water Aid, Oxfam, we do local stuff at schools and housing. It's really important to keep that going. I can't just pay off my overdraft and say, 'Sod that.'" Do most people think he makes a fortune from the festival? "Yes they do, but they don't know. They just need to speak to my bank manager."

The festival was not started as an act of altruism. It may have only cost £1 a ticket in 1970, but at the time he said: "The farm is such a dead loss we've got to look at other ways of making money." These days it's anything but a loss. The money he has made, he says, is largely from farming. Eavis is quick to tell you that his herd is the highest yielding in Somerset and ninth highest in the country. "If we milked three times a day we'd be top, but we only milk twice a day."

I ask him how he feels about badgers. It's a delicate subject. On the one hand, he has a badger sett on the farm that is much-loved by festival-goers; on the other, badgers are thought to be responsible for TB in cows. "As a dairy farmer I am not on the side of the badger. They've also uprooted all the orchids and killed all the hedgehogs. They're treated like a protected species, but they're quite a damaging animal."

Eavis's cows have not had TB. Is he in favour of the cull? "In certain circumstances." Such as? "My first love, apart from my wife and children, are the dairy cows, because we've been doing dairy cows at Worthy Farm for 150 years. We've got about 400. If I thought for a moment badgers would infect my cows, I know which side I'd be on. There's a farm three miles down the road that lost 500 cows to TB. That's the whole of his career, and his father before him, and his grandfather, just destroyed in one fell swoop. It is serious, I'm telling you."

What if a cull included Worthy Farm? "We're not inviting people to destroy our badgers, OK? But in some areas there are problems that need to be tackled." The reality is that if there were a cull, it would include all the local farms.

Eavis regards himself as a farmer first and foremost. And the farming is easier to reconcile with his Methodism. "Being a farmer is more authentic than organising Glastonbury. You're rearing cattle, you're feeding people. There's no branding, no sales pitch, it's just a natural way of living. There's no contamination, no transport, trains or planes. The festival has got a lot of other stuff – drugs, drinking, branding. It's a different thing."

He pauses. "Don't get me wrong," he says. "I love the festival. That's why it's so successful – because I love it so much. But you offered me a preference, and I'm just telling you why I prefer the farm."

When Jean was alive, they were going to stop holding the festival in 2000. Then she died, and he felt he had to go on. A while ago, he said he'd stop in 2011. But that didn't come to pass, either. Now he's hoping to keep going until its 50th anniversary in 2020. He'll be 84 then.

His friend Peregrine Eliot, Earl of St Germans, who runs the Port Eliot literary festival, has said that Glastonbury hasn't been the same since it erected its £1m fence to keep out the gatecrashers in 2002; that it's become more corporate. "That's not true," Eavis says. "He doesn't need a fence because people don't go to his show. Haha!" And in fact, says Eavis, in typical bullish fashion, the festival's in the best nick ever. "The programme's better than ever … I'm particularly looking forward to Nick Cave and Steve Winwood. And wait till you see the new loos. No emptying – it goes straight into the ground. After 43 years, we've finally got the perfect loo." With that he roars merrily, and heads for the Land Rover.

Glastonbury festival has been staged most years since Michael Eavis, owner of Worthy Farm, first organised the Pilton festival in 1970. The Rolling Stones may have captured headlines for this year's event, but in six short videos we look at the lesser-known contributors to the world-famous music extravaganza